This change adds access_rules as a parameter for creating application
credentials, and also adds the ability to list access rules and to
retrieve and delete individual rules. Directly creating an access rule
or updating one is not supported.

bp whitelist-extension-for-app-creds

Depends-On: https://review.opendev.org/671374
Change-Id: I490f1e6b421d4f36f588f83a511ce39b9b4204e2

Add support for creating, reading, and deleting application credentials.
Application credentials do not support updating.

Keystoneclient does not handle authentication with application
credentials. This is done in keystoneauth. Additional work will be
needed in python-openstackclient to support both CRUD and auth for
application credentials.

bp application credentials

Change-Id: I21214238deac2c45f2f2d666287c2ae106955ab1